Understanding and Optimizing Peracetic Acid Disinfection Processes Using Computational Fluid Dynamics: The Case Study of Nocera (Italy) Wastewater Treatment Plant R. Maffettone 1(&) , F. Crapulli 2 , S. Sarathy 4 , L. Pucci 4 , L. Rizzo 5 , G. Lofrano 6 , G. Raspa 7 , S. Guadagnuolo 4 , R. De Rosa 4 , A. Giuliani 4 , M. Carotenuto 8 , S. Luise 8 , and D. Santoro 3 1 Department of Civil Engineering, McGill University, Montreal, Canada 2 Department of Chemical and Biochemical Engineering, Western University, London, ON, Canada 3 Trojan Technologies, London, ON, Canada 4 CONSORZIO NOCERA AMBIENTE, Nocera Superiore, SA, Italy 5 Department of Civil Engineering, University of Salerno, Fisciano, SA, Italy 6 Department of Chemistry and Biology, University of Salerno, Fisciano, SA, Italy 7 Department of Chemical Engineering Material and Environment, La Sapienza University, Rome, Italy 8 Hach Lange, Milan, Italy Abstract. In this paper, a modeling study focused on optimizing the PAA disinfection performance in a full-scale contact tank currently operated at the Nocera (Italy) Wastewater Treatment Plant is presented. The disinfection pro- cess was monitored for over 2 weeks by collecting full-scale data on plant variability in flow, disinfectant demand/decay and microbial concentrations. A computational fluid dynamics (CFD) model of the contact tank describing the PAA disinfection process was developed. Four disinfection scenarios were analysed using an Eulerian-Lagrangian approach: (a) PAA disinfection under the existing conditions; (b) PAA disinfection with PAA pre-mixed prior to the contact tank; (c) PAA disinfection with PAA dosed with 8 injection points distributed over the entire length of the inlet weir; (d) PAA disinfection in an optimized plug-flow contact tank. All these scenarios were analysed for the same operating conditions, i.e. fixed flow, PAA demand/decay and inactivation kinetics. The model-based analysis clearly revealed that the optimized contact tank (scenario d) was able to achieve a much higher contact and extended between microorganisms and disinfectant thus resulting into a five-fold increase in microbial inactivation. Keywords: Peracetic acid Á Wastewater disinfection Á Computational fluid dynamics © Springer International Publishing AG 2017 G. Mannina (ed.), Frontiers in Wastewater Treatment and Modelling, Lecture Notes in Civil Engineering 4, DOI 10.1007/978-3-319-58421-8_110